Improved process for production of aerosol latex with centrifugal force

ABSTRACT

The preparation of aqueous latices from solvent dispersions of elastomers and other high polymer compositions has presented problems including excessive viscosity during processing and foaming and coagulation, which have produced losses and increased costs. Herein combinations of steps are disclosed which reduce or eliminate various of these problems; enable the preparation of latices from high solids, high viscosity cements as well as from high solids cements of low molecular weight polymer; enable preparation of latices of grafted or filler extended or filler reinforced elastomers; enable preparation of latices of low molecular weight polymer which are then modified to materially increase the molecular weight of the polymer and/or the latex particle size; and enable the preparation of improved latices both dilute and of high solids contents, which are useful for example for adhesive and film forming purposes. The process in common with that of related copending applications is characterized, inter alia, by the establishment of a flow of latex through the separating zone and the impingement on said flow of the coalesced latex droplets from the solvent vapor stream in which they are delivered to the separator, and in certain embodiments by the use of particular additive materials. New combinations of steps and of apparatus for performing the same are also disclosed and claimed. The part of the process disclosed and claimed herein includes the improvement which consists essentially in subjecting the flow of aerosol made up of latex droplets in a solvent vapor containing gaseous phase, to the action of centrifugal force for effecting coalescence of the droplets into larger droplets in the flow, before separation thereof from the flow, to facilitate such separation. The process disclosed is applicable to the production of latices from specified rubbery and non-rubbery polymer compositions, and certain of such latices are new and useful products also claimed herein.

United States Patent [191 Burke, Jr.

[451 July 1, 1975 54 PROCESS FOR PRODUCTION OF AEROSOL LATEX WITHCENTRIFUGAL FORCE [75] Inventor: Oliver W. Burke, Jr., Ft.

Lauderdale, Fla.

[73] Assignee: Exxon Research and Engineering Company, Linden, NJ.

22 Filed: Sept. 2, 1971 21 Appl. No.: 177,465

Related U.S. Application Data [60] Division of Ser. No. 767,790, Oct.15, 1968, Pat. No, 3,622,127, which is a continuation-in-part of Ser.Nos. 621,997, March 7, 1967, Pat. No. 3,503,917, and Ser. No. 691,823,Dec. 19, 1967, abandoned.

[52] U.S. Cl. 260/29.6 R; 260/297 R [51] Int. Cl. C08f 45/24 [58] FieldofSearch 260/296 RM,29.6 CM,

260/296 XA, 29.6 PM, 29.6 PC, 29.6 PT, 29.6 EM, 29.7 B, 29.7 EM

[56] References Cited UNITED STATES PATENTS 3,277,037 10/1966 Halper eta1. 260/296 XA X 3,281,386 10/1966 Moss et al 260/29] EM 3,294,71912/1966 l-lalper et al. 260/296 XA X 3,310,515 3/1967 Halper et a1.260/296 PM Primary Examinerl-larold D. Anderson Attorney, Agent, orFirm-Hall & Houghton [57] ABSTRACT The preparation of aqueous laticesfrom solvent dispersions of elastomers and other high polymercompositions has presented problems including excessive viscosity duringprocessing and foaming and coagulation, which have produced losses andincreased costs. Herein combinations of steps are disclosed which reduceor eliminate various of these problems; enable the preparation oflatices from high solids, high viscosity cements as well as from highsolids cements of low molecular weight polymer; enable preparation oflatices of grafted or filler extended or filler reinforced elastomers;enable preparation of latices of low molecular weight polymer which arethen modified to materially increase the molecular weight of the polymerand/or the latex particle size; and enable the preparation of improvedlatices both dilute and Of high solids contents, which are useful forexample for adhesive and film forming purposes. The process in commonwith that of related copending applications is characterized, interalia, by the establishment of a flow of latex through the separatingzone and the impingement on said flow of the coalesced latex dropletsfrom the solvent vapor stream in which they are delivered to theseparator, and in certain embodiments by the use of particular additivematerials. New combinations of steps and of apparatus for performing thesame are also disclosed and claimed. The part of the process disclosedand claimed herein includes the improvement which consists essentiallyin subjecting the flow of aerosol made up of latex droplets in a solventvapor containing gaseous phase, to the action of centrifugal force foreffecting coalescence of the droplets into larger droplets in the flow,before separation thereof from the flow, to facilitate such separation.The process disclosed is applicable to the production of latices fromspecified rubbery and non-rubbery polymer compositions, and certain Ofsuch latices are new and useful products also claimed herein.

2 Claims, 6 Drawing Figures PROCESS FOR PRODUCTIONOF AEROSOL LATEX WITHCENTRIFUGAL FORCE CROSS REFERENCE TO RELATED APPLICATION Thisapplication is a division of my application Ser. No. 767,790 filed Oct.15, 1968 now U.S. Pat. No. 3,622,127 and has been filed pursuant to arequirement for restriction entered therein, said application Ser. No.767,790 having been a continuation-in-part of my applications Ser. No.621,997, filed Mar. 7, 1967 (now U.S. Pat. No. 3,503,917 issued Mar. 31,1970), and Ser. No. 691,823, filed Dec. 19, 1967 now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to the production of aqueous latices from solvent dispersions ofhigh polymer compositions and aims generally to provide improved processand apparatus combinations therefor, and new products produced thereby.

2. Description of the Prior Art To date, in the practical art, syntheticlatices of high polymers have been primarily prepared by emulsionpolymerization, and such practice has not been applicable to highpolymers made by essentially anhydrous catalyst polymerizations. It hasbeen proposed to prepare aqueous latices of high polymers from solventsolutions thereof by processes of the type which comprise the generalsteps of (1) providing a dispersion or cement of the polymer in avolatile organic solvent for the polymer, (2) adding to such dispersionwater and an aqueous emulsifier therefor and emulsifying the same toproduce an emulsion, (3) stripping the volatile organic solvent from thesaid emulsion, and (4) recovering the resulting latex product. However,in the practical art difficulty has been experienced in attempting torender such proposed processes commercially feasible, inter alia, inthat (l) solvent dispersions or cements of the high polymer materials,unless quite dilute, have high viscosities, which have rendered itimpractical to produce raw emulsion particles of precursor latexparticle size from such dispersions when their viscosities have beenover 3,000 to 10,000 centipoises; and when dilute, require the use ofundesirably high quantities of emulsifier and the stripping ofundesirably large quantities of solvent; (2) in that the emulsions havetended to foam excessively during stripping; (3) in that the emulsionshave tended to form coagulum by drying out especially on contact withheated surfaces, during the stripping and/r concentrating processes; and(4) in that all of these problems are accentuated as the aqueous contentof the emulsion is reduced.

SUMMARY OF THE INVENTION When the molecular weight of a polymer is high,in order to form cements without excessive viscosity, which preventsemulsification 0f the cement, it is necessary to prepare the cementswith low polymer and high solvent content. When these dilute cements areemulsified and then stripped of their high solvent content, theresulting latex contains an excess of emulsifier and its latex particlesare very small. The excess of emulsifier is undesirable in many uses,e.g. in the use of the latex for producing latex foam. And when theaverage particle size of the latex is low, e.g. about 500 A, then theviscosity of the latex rises rapidly with increase in solids contentreaching 3,000 centipoises at about 40 percent solids. It is usually thedesire of the industrial users of polymer latex that the polymer be ofhigh molecular weight, that the solids content by high, i.e. in therange of 60-70 percent, that the viscosity of the latex be low (e.g. notmore than 5,000 centipoises for adhesives, and as low as 1,000centipoises for the production of latex foam products), and that thecontent of emulsifier be low. In various embodiments of thepresentinvention, singly and in cooperating combinations, provisions aremade for attaining certain of the above desiderata, namely: (1) byproviding processes for obtaining high molecular weight latices fromcements of low molecular weight polymers with consequent savings ofsolvent, emulsifier and energy costs; (2) by providing processes forimproving the efficiency of the cement emulsifying operation withconsequent improvement in particle size (e.g. by improving the averagesize of the cement particles and/or reducing the particle sizedistribution thereof, which cooperates with later steps in obtaining theabove objectives; (3) by providing processes for stripping the solventfrom the dispersed particles of the emulsion in the form of an aerosolas hereinafter defined with improved control of temperature and rate ofvaporization and conse quent reduction in materials losses, e.g. bycoagulum formation; (4) by providing processes for improving thesegregation'and separation of the stripped latex from the solvent/vaporphase of the aerosol with consequent reduction or avoidance of coagulumlosses and foaming; (5) by providing processes for increasing themolecular weight and/or adding polarity to and/or augmenting theparticle size of the dispersed phase of the latex, and/or increasing thesolids content and/or reducing the viscosity of the latex.

In accomplishing the aforesaid objects, in respective embodiments of thepresent invention conditions are created combinations of which alleviatethe aforesaid problems and render practical the production of desirableaqueous latices from solvent dispersions of polymer compositions. Theseconditions, inter alia, include, severally and in cooperatingcombinations:

1. The use of particular solvents for the polymers which are essentiallyimmiscible with water in liquid phase, and which have boiling pointsless thant the boiling point of water at atmospheric pressure, or whichform azeotropes with water which have boiling points less than theboiling point of water at atmospheric pressure, and preferably solventswhich have boiling points higher than that of water but which formazeotropes with water that have boiling points lower than that of water,which preferred group comprises especially the aromatic solventsincluding toluene, the xylenes, ethyl benzene, cumene, etc., thesesolvents for the polymers being organic solvents which dissolve thepolymer without any change of chemical composition thereof.

2. The formation of relatively high solids cements of low, intermediate,or high molecular weight polymer compositions with the solvent thereforselected as aforesaid, which in particular embodiments of the inventionmay have viscosities of over 1,000 centipoises preferably over 3,000centipoises, and even higher, which viscosities can be maintained withinlimits and/or be tolerated because of other cooperating steps of theprocess.

3. The employment of ultradispersing equipment, in certain embodimentstogether with a homogenizer which forces the aqueous emulsion at a highpressure of 1,000 to 10,000 p.s.i. through a constriction, to reduce thepreferred cements in the presence of the aqueous phase and emulsifier toparticles of precursor latex size preferably of sizes producing a latexof relatively narrow particle size distribution, and preferably one ofan average size in the upper part of the colloidal size range; suchultradispersing system combining mechanical, hydraulic, and ultrasonicshear, impact, and vibrating phenomena, which applicant has shown toeffect such reduction notwithstanding that such cements may have veryhigh viscosities of up to 3,000 to 10,000 centipoises or higher, andnotwithstanding that such cements may have their viscosities increasedby the incorporation of fillers so that they will be contained withinthe precursor latex particles themselves for producing betterreinforcement, as is contemplated in certain embodiments of the presentinvention; and such high pressure homogenizer preferably being of theresiliently restricted orifice type. The said conditions thus enable thequantities of emulsifier and solvent to be kept relatively low whilesimultaneously providing precursor latex size particles facilitating theremoval of solvent therefrom.

4. The employment in the process of an emulsifier system which will forma stable aqueous emulsion of the solvent/polymer solution (principallysolvent) and which will also form a stable emulsion, and finally astable latex, of the polymer itself.

5. The removal of solvent from tiny droplets of the so formedoil-in-water emulsion by introducing the same, as a discontinuous phase,into a flow of gas comprising essentially steam as an initial continuousphase, while subjecting the two phases together to a decrease ofpressure and while maintaining the temperature of both phases within thelimited range for stability of the emulsion. Solvent is thus vaporizedfrom the precursor latex sized particles while maintaining theirstability, so that substantially all the solvent is vaporized into thegaseous continuous phase which thus becomes a gaseous stream carryingaqueous droplets having one or more latex size polymer particles perdroplet, the preferred droplet size range being that of an aerosol ofwhich the dispersed phase may comprise colloidal and larger sizeddroplets in a steam/solvent vapor continuum.

6. The separation of the resulting droplets of latex from the gaseouscontinuous phase by coalescencing and collecting the same while avoidingdeleterious agglomeration and foaming. The coalescing step may bepracticed in several ways which are quite distinct. One of theseprocedures employs centrifugal force, which may be number of times theforce of gravity, to aid the coalescence of segregation of the latexwithout foaming. A particular embodiment of this species subjects boththe latex phase and the gaseous phase to centrifugal force undercontrolled pressure conditions, as in a centrifugal pump delivering froma region of higher pressure to a region of lower pressure. Anotherprocedure passes the two phases i ls" bulently or tortuously throughmeans defining elongated path to effect the coalescence or segregationinto droplets large enough to be separated from the gaseous phase ashereinafter described. After the coalescence or segregation of theliquid phase in one of these manners, the twophases are passed to acollecting means, preferably of the cyclone separator type, and thegaseous phase is then passed to a condensing system from whichnon-condensibles are pumped by any suitable vacuum pumping means.Throughout the stripping, coalescing and collecting steps: (a) thetemperature of the two phases is maintained within the limitedtemperature range for stability of the emulsion, preferably bycontrolling the initial continuous phase in temperature essentially tonot exceed the limiting temperature for stability of the emulsion and inquantity to be sufficient to substantially effect the stripping of thesolvent, and by controlling the temperature and quantity of the emulsionbeing dispersed therein; (b) the delivery of substantially all of thesolvent to the gaseous continuous phase is essentially effectedpreferably in a single pass by appropriate design of the capacity of theapparatus, but when it is desired to employ apparatus of more limitedcapacity, is achieved in part in a first pass through the strippingapparatus and is completed by an additional pass or passes of thepartially stripped material through the same equipment, i.e. by arecycle, and (c) the flow of gas comprising steam as the initialcontinuum preferably consists entirely of steam expanded, when it firstcontacts the emulsion, to sub-atmospheric pressure and to a temperaturenot detrimental to the latter, where any substantial quantity of solventis being stripped from the precursor latex sized particles, but, underconditions where it is desired to augment the volume or velocity of theinitial continuum, being augmentable by including a minor proportion ofnon-condensible gas or of the solvent in the said flow of gas, for whichpurpose a minor proportion of the effluent gas phase from the separator,or of the azeotrope remaining in said gas phase after condensation ofunazeotroped water vapor therefrom, may be recycled to constitute a partof the initial continuum, or in particular embodiments, by theintroduction of only a part of the steam at the point at which theemulsion is injected, and augmenting the flow and solvent vaporation bythe introduction of further steam downstream from the point of emulsionintroduction.

7. The latex delivered by the separator is a stable latex suitable forany use for which its solids content adapts it. It is also at atemperature within the limited range for stability of the emulsion andthe invention further contemplates that this separated latex, preferablywithout cooling, may be recycled and be again passed through thecentrifugal segregator or the elongated path segregator, or recycledonly through the heat exchanger if desired, and particularly toconcentrate the latex by removing water therefrom, when a product ofhigher solids content is desired. When concentrating stripped latex itis desirable to cut off the supply of initial raw emulsion and the steamand to supply the external heat to the latex through the walls definingthe elongated path, eg a plate heat exchanger to vaporize water from thelatex with the aid of reduced pressure and to separate the water vaporand latex in the vacuum separator. Where it is advantageous to removesolvent and concentrate the latex continuously then separate equipmentunits are coupled together, one unit for stripping of the solvent fromthe raw polymer-solvent emulsion and the other unit for concentrating ofthe stripped latex and advantageously may be interposed between the twounits high pressure coalescing equipment. The concentrated latexeffluent as a discontinuous phase from the heater exchanger with theevolved water vapor which is at least a part continuous phase, may againbe separated in the separator, the vapor phase passing to the condensingequipment, and any uncondensables again passing therefrom to the vacuumpumping equipment.

8. While for economy of equipment it is sometimes preferred to employthe same segregator, with adjustment of appurtenant equipment as abovedescribed, for effecting both the stripping and the concentration, thecapacity of the segregator may be adjusted to the load to be served, andwhen it is desired to concentrate the stripped latex without suspendingthe stripping operation of the equipment, one or more separate elongatedpaths or the like may be provided for this purpose, which may terminatein any desired separator equipment, but which preferably terminate inthe same collector or separator equipment. The desired concentration maybe effected in a single pass, or, if desired, in a plurality of recyclesthrough the same or different concentrating paths. When the latex beingconcentrated is returned to the same segregating, separating, orcollecting equipment, it is preferably distributed on the walls of thesegregator, separator, or collector in such a way that the droplets ofstripped latex being delivered thereto with the solvent vapor will beimpinged on the recycled latex, as it has been found that this proceduretends to minimize the formation of coagulum and form.

9. The water recovered in the condensing equipment is distilled watersaturated with the stripped solvent, and in accordance with the presentinvention it is preferred to recycle this recovered water for use inpreparing the emulsion of the precursor latex sized particles of solventsolution of the high polymer composition.

10. Various of the above conditions are common to embodiments of processdisclosed in the aforesaid copending applications, but the inventionherein disclosed includes various additional features and combinationsof features more particularly adapted to cooperate with various of theaforesaid features to effect modification of the physical and/orchemical characteristics of the latex produced and/or to facilitate theoperations for producing the same. In particular, these additionalcooperating features have advantages separately and collectively (a) toenable one to process to latex polymer material of intermediate or lowmolecular weight which facilitates the processing operation, and toconvert the lower mo lecular weight materials in the latex into highermolecular weight form, this latter step being accomplished with the aidof cross-linking agents with or without cross-linking monomers; (b) toenable one to convert the solvent polymerized hydrocarbon polymerswhich, for example, have good moisture resistance, into intermediatelatices and to modify such latices to form therein interpolymerscontaining selected polar groups which impart specific propertiesthereto not inherent in the hydrocarbon polymers, eg by incorporatinginto butyl rubber or hydrocarbon resin plastomer, orethylene-propylenecopolymer elastomer, in latex form, carboxyl, hy-

droxyl, amide, or other groups desirable to better adapt such polymersfor bonding, coating and related uses in, for example paper manufacture;(c) to enable one to modify the latices to have narrow particle sizedistributions and average particle sizes near the upper end of thecolloidal size range of 500 to 10,000 A; and (d) to enable one toaccomplish the foregoing in various combinations to yield latices ofhigh solids content, e.g. 60 to 68 percent solids, having various ofsuch characteristics separately and in combination.

The objects of the invention, severally and interdependently, are toprovide new apparatus features and new combinations of steps, whichcontribute to produce an improved process and which enable theproduction of new latices which may contain not only polymers andcompounding ingredients such as fillers, but which in preferredembodiments may contain such compounding ingredients, e.g. reinforcingfillers, within the high polymer latex particles. Other objects andadvantages of the invention will be apparent from the above generaldescription and the following more particular descriptions of preferredembodiments thereof, which, however, are illustrative but notrestrictive of the invention, the scope of which is more particularlypointed out in the appended claims.

By the term latex as used herein is meant an aqueous suspension ofcolloidal polymer particles exhibiting Brownian movement and saidpolymer thereof includes the following types:

i. homopolymer,

ii. interpolymer including block and graft polymer,

iii. hydrocarbon polymer iv. polar polymer,

v. cross-linked polymer,

vi. non-cross-linked polymer,

vii. polymer composition comprising polymer material selected from (i)through (vi) above and compounding ingredients including reinforcingfillers and/or non-reinforcing fillers.

By the term colloidal particle or colloid as used herein is meantparticles in the size range of 500 A to 10,000 A diameter. By the termprecursor latex particle size (applied to the dispersed particles ofsolvent containing polymer in the emulsion) is meant particles of suchsmall size that they will be of stable latex particle size when relievedof their solvent content.

BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawing:

FIG. 1 is a flow sheet or diagram illustrating the sequences of stepsand flow of material in typical embodiments of process according to theinvention.

FIG. 2 is a diagram of a preferred form of equipment for preparing theemulsion, corresponding to portions 7-13 of FIG. 1, the correspondingelements having the same numerals raised by 100, and respective partsthereof being designated by modifying letters.

FIG. 3 is a similar diagram of a preferred form of device for dispersingthe emulsion of solvent/polymer cement into the steam flow, andsegregating and separating the latex phase from the vapor phase, andfurther treating the latex phase, corresponding to portions 14 andfollowing of FIG. 1.

FIG. 4 is a more or less diagrammatic elevation partly cut away of apreferred embodiment of the portion 14 of FIG. 1..

FIG. is a more or less diagrammatic elevation, partly cut away, of apreferred form of separator corresponding to portion 16 of FIG. 1.

FIG. 6 is a more or less diagrammatic horizontal cross-section taken online VI-VI of FIG. 5.

DESCRIPTION OF PREFERRED EMBODIMENTS a. In General In the preferredembodiments illustrated in FIG. 1, the high polymer (1) e.g. elastomerand/or plastomer material as hereinafter described, is prepared as ahigh polymer composition 4 for conversion to a cement, as by working inappropriate masticating, comminuting, or attenuating equipment 2, suchas a rubber mill, Banbury, comminutor, extruder, or the like. Inaccordance with the aforesaid applications provision may be made forincorporating one or more known polymer compounding ingredients 3, e.g.rubber reinforcing filler, into the said polymer composition in such away that the ingredients 3 are thereafter contained within the polymerparticles of the latex being formed, for which purpose the saidingredient or ingredients 3 may be worked into the high polymer 1 byworking therewith in the masticating equipment 2. By such procedure thesaid polymer ingredients may become fixed to the compounding ingredient,i.e. the polymer particles can become reinforced by the fillers, and ineffect become so intimately attached thereto, or embrasive thereof, asto retain the same when dispersed as a cement. In the case ofcompounding ingredients desired to be incorporated in the latexparticles, but not requiring working with the polymer itself, suchingredients 3 may be fed into the cement forming equipment or dissolver5 independently of the said polymer composition 4, as is also indicatedin FIG. 1.

In the cement forming equipment or mixer or dissolver 5 which may alsocomprise a disperser, the high polymer composition 4 is combined andpreferably stirred or otherwise worked with solvent 6 appropriate forthe high polymer and for the process, as further described herein, toform a solvent cement 7 of the high polymer composition 4 and of anyextraneously added compounding ingredients 3, the adequate dispersion ofwhich in the cement may require vigorous working, which may even beaccomplished by the passage of the cement through a suitable dispersingequipment 7a.

The solvent/polymer cement 7 is then combined with emulsifier 8appropriate for the high polymer and the process, and with water 9 in acourse emulsion mixing equipment 10 where the ingredients are mixed,preferably with the aid of heat, to form a course cement in wateremulsion 11, which is then passed one or more times through anultradispersing equipment 12, preferably of the type hereinafterdescribed, which breaks up the relatively large particules ofsolvent-cement forming the discontinuous phase in the course emulsion 11into particles of such small size that they will be of stable latexparticle size when relieved of their solvent content, and preferablynear the upper limit of such size.

In my aforesaid applications the course cement-inwater emulsion 11 waspassed one or more times, usually six to 12 times, through one or moreso-called ultradispersers 12 of the Moulds type more fully describedhereinafter, in order to accomplish a sufficient reduction of latexparticle size, and the resulting fine emulsions had rather wide rangesof cement droplet size distribution. In the present improvement, theemulsion of high viscosity solvent/polymer cement prepared with arelatively large range of droplet size distribution by theultradisperser equipment 12, adjusted if necessary to an appropriatetemperature, by the cooler 13A, by-pass 13B and/or heater 13C, is fed bysuitable positive displacement, e.g. plunger pump means 13D, to a highpressure homogenizer preferably of the resiliently restricted orificetype 13E at pressures in the range of 1,000 to 10,000 p.s.i., forreducing the particle size distribution of the fine emulsion. Theresulting emulsion of reduced particle size distribution is preferablycooled by a cooler 13F before being delivered to storage means such as atank 13, for subsequent treatment. As indicated in FIG. 1 the emulsifiermaterial 8 may be formed into an aqueous emulsifier solution 8" withwater 9' saturated with solvent or with water 9" from an extraneoussource.

The resulting relatively cool fine cement-in-water emulsion of precursorlatex size particles 13 as'in the aforesaid applications is thenconverted into an aerosol of which the dispersed phase may comprisecolloidal and larger sized droplets in a steam/solvent vapor continuum,and is therein stripped of its solvent content without excessive foamingand while avoiding formation of coagulum. In accordance with the presentinvention provision is perferably made by which the temperature andpressure and the rate of evaporation of solvent from the aerosoldroplets may be controlled to facilitate maintenance of the stability ofthe aqueous emulsion during the stripping of the solvent to produce anaerosol of latex of the polymer, as is hereinafter more fully describedin connection with FIGS. 3 and 4. As in the aforesaid applications, theformation of the aerosol is preferably accomplished by providing a flowof steam 14a as an initial continuous phase and introducing theoil-in-water emulsion of precursor latex sized particles 13 as adiscontinuous phase into the flow of steam in a mixer 14 as the initialcontinuous phase, whereby volatile solvent 6 is vaporized to become thecontinuous phase or the principal part thereof, and a correspondingamount of steam is condensed to supply the heat of vaporization for thesolvent and become added as water to the discontinuous phasev Asexplained in connection with FIGS. 3 and 4, in certain embodiments ofthe present process preferably only a part of the steam is supplied at afirst station where the emulsion of polymer/solvent solution isintroduced, and the remainder of the steam is introduced at one or morestations downstream from said first station in conducting the phasetransition. As this phase transition is accomplished the resultinggaseous and non-gaseous phases are usually in a form resembling anaerosol and the aerosol droplets must be coalesced, with minimumcoagulation, to form a latex separated from the vapor phase. Thiscoalescing step is hampered by the fact that the coalescing materialtends to produce large quantities of foam. The coalescing must thereforbe conducted in a manner to either prevent or minimize the formation offoam or successfully defoam the coalesced materials.

This coalescing step may be practiced by subjecting the gaseous andnon-gaseous phases to a decrease in pressure, while passing them througha segregator or coalescer and while maintaining the temperatures of theflows within the limited range for stability of the emulsion l3, and thecoalesced droplets, now definitely of greater than aerosol size, arecollected in the form of a bulk latex from the gaseous continuous phase.As is more fully described in connection with FIG. 3, in certainembodiments of the present invention, the coalescing is accomplished bysubjecting the aerosol, on its way to a reduced pressure separator 16,to the action of centrifugal force for effecting segregation orcoalescence of the non-gaseous phase, as by passing the gas and latexphases of the aerosol through a centrifugal pump, and preferably acentrifugal pump having the type of pump rotor, pump chamber and inletand outlet means illustrated in U.S. Pat. No. 3,324,798. The finalseparation or collection may be attained by delivering the flows fromthe segregator 15 into a separator or collector 16, from the lower partof which the latex is drawn, and from an upper part of which thecontinuous phase is passed to condensing equipment 17 maintained undervacuum, preferably a vacuum of the order of 28 to 29 inches of mercury,by withdrawal of uncondensed gases therefrom by vacuum pumping equipment18, e.g. a steam jet, and the separator of collector 16 may be ofvarious forms and may even be incorporated with a segregator 15 as isdescribed in said copending application Ser. No. 691,823.

Still referring to FIG. 1, as explained in said copending applicationthe high polymer composition latex 19 withdrawn from the separator 16may be delivered as product 20, or may be recycled as indicated at 21and be again fed as discontinuous phase through the steam disperser 14and/or the segregator 15 for removal of residual solvent therefrom asabove noted, either separately or concurrently with additional emulsion13 as is indicated by the value symbols between 13 and 14 and in thelines from 168 to 14 and from 16B to 16 in FIG. 1; or it may be cycledthrough a different or the same heater and separator (21 and 16) forconcentrating the latex, in which event the latex is heated to evaporatewater therefrom under sub-atmospheric pressure at temperatures withinthe limited temperature range for its stability, externally to its flowpath (in 21) from the valved heat source shown connected to 15 and 21,while the supply of steam internally of the path from the valved source14a is reduced or cut off as aforesaid. When such concentrating step hasbeen employed, the product resulting therefrom will be a latex ofincreased solids content.

The present invention, however, makes provisions which may be employedfor modifying the latex 20, preferably while it still contains residualsolvent from having been in contact with the aqueous/solvent gaseousphase in the stripping separator 16 (see also 216, FIG. 3 and FIGS. 5and 6). These provisions are illustrated at 24 and following in FIG. 1herein, and in particular reside, in various embodiments of theinvention, in employing the high pressure orifice type homogenizer toeffect, or facilitate, the contemplated latex modifications. Thus, inthese embodiments of the invention, the latex of intermediate solidscontent, preferably while still containing residual solvent, may bemixed in a hold tank, mixer, or proportionate feeder 24 withpolymerization catalyst 24a and monomer material 24b, and afterappropriate adjustment of its temperature, as by a heat exchanger means25, may be passed at high pressure, e.g. 1,000 to 10,000 p.s.i.,

through an orifice type homogenizer to promote intimate association ofthe mixed ingredients. Such intimate association at high pressure underthe extreme conditions of attenuation and working obtained in thehomogenizer 26 can in certain instances partially or completely effectpolymerization of the monomer materials in intimately associated orgrafted form with the polymer, and in cases in which further treatmentby subjection to heat energy or to the effect of high energy radiationis required to complete the polymer modification to the desired degree,the intimate dispersion and high pressure working in the homogenizer 26facilitates such completion to produce a uniform product in the reactor,e.g. curing or polymerizing apparatus 27, to which the effluent from thehomogenizer 26 may be delivered for such energy treatment. The modifiedpolymer latex delivered by the orifice type homogenizer 26 or the energytreating reactor 27, as the case may be, is delivered to storage 29,preferably through a cooler 28, pending delivery as by a pump 30 forfurther treatment in heating and separating apparatus 31 and 32, whichmay be of the type shown at 1220 and 1216F in FIG. 3, hereinafterdescribed. In this further treatment residual solvent, odors, andunreacted monomer, if any, may be removed, and if desired the latex maybe further concentrated. The modified latex from separator 32, which ineach event will have, along with other modifications, a higher solidscontent than the latex 20, may be passed by a pump 34 to product storage36, preferably through a cooler 35.

In certain embodiments of the invention, the operations up to point 20may be conducted to form the cement and latex 20 of low molecular weightpolymer, which enables a cement of higher solids content to be employedwithout having to deal with excessively high viscosity, and monomer 24band cat. 24a, and temperature in the homogenizer 26 or apparatus 27 maybe employed in such quantities and degree as to materially augment themolecular weight of the polymer, and especially when it is desired tohighly augment such mo lecular weight, polymer cross-linking agent 24cmay be added in the mixer 24, for intimate association and reaction inthe homogenizer 26 or apparatus 27.

In certain other embodiments of the invention, the size of the particlesof polymer in the latex is increased as by conditioning the latexdelivered from 24, preferably containing residual solvent, in a mannerwhich will enable its dispersed particles, when finer than desired, tobe caused to coalesce in groups of two or'more particles, so as todouble or triple the average size of the solids particles of the latex.To this end a stable latex delivered from 24 may be heated as at 25, toa temperature just below or approaching the maximum temperature forstabilization of the latex to sensitize the latex as by substantiallyreducing the proportion of its emulsifier which is stabilizing the latexparticles, and the sensitized solvent containing latex is then passed ata pressure in the range of 1,000 to 10,000 psi. through the constrictionof the homogenizer 26. Under these conditions, this invention shows, theextreme pressure and intimate contact and working of the sensitizedparticles of the latex 24 in the apparatus 26 can cause the sensitizedparticles to cleave together to form larger particles as aforesaid,reducing the viscosity and increasing the average particle size of thelatex before the final treatment in the apparatus 31 and 32.

In still other embodiments of the invention, the destabilization of thelatex delivered from 24 may be effected by heating at 25 as justdescribed, and the destabilized latex may then be cooled by at least F.in a cooling section of the heat exchanger 25, and then be immediatelysubjected to the high pressure working in 26, following which the latexis allowed to dwell, e.g. in storage 29, until it becomes restabilizedby aging.

And in still further embodiments of the invention, the destabilizationof the latex at 24 is effected by adding a chemical destabilizing agent24d, e.g. an acid or acid salt and preferably an acid or a weakly acidicvolatile acid salt, which can be removed from the latex in the apparatus31 and 32, or an acidic additive desired in the latex, as hereinafterdescribed, in a quantity less than that which would coagulate the latex,and the thus destabilized latex is then treated in the high pressurehomogenizer to increase its average particle size as aforesaid And inthose embodiments of the invention in which the chemical destabilizer isnot removable or removed from the latex being delivered to storage 36,an alkali, or additional emulsifier, may be added, as at 39, to restorethe latex to a stable condition. For example, when acid has been addedwhich imparts to the latex a pH of less than 6 during the treatment inhomogenizer 26, the alkali may be added at 39 to adjust the pH of thelatex to about 7. The final stripping, deodorizing, and/or concentratingin separator 32 is preferably effected with the aid of condensingequipment 37 and vacuum pumping apparatus 38, and when such equipmentproduces a yield of recoverable fluid, e.g. pure water, such may bereturned for reuse, e.g. to the water supply 9, as shown.

In a still further embodiment of the invention, exemplified in FIG. 3,the stripped latex 324 still containing residual solvent, with orwithout pretreatment by passage at high pressure through theconstriction of homogenizer 326, is subjected to concentration,deodorizing, and stripping of residual solvent in a heating apparatus1220 and separator 1216, and is then, as a finished high solids latex,subjected to heating to an appropriate temperature at 1225, and furthertreatment by passage at a high pressure of 1,000 to 10,000 psi. throughthe constriction of a homogenizer 1226, with or without prior mixing inmixer 1224 with polymerization catalyst 1224a and a monomer material1224b and/or cross-linking agent 12240 for effecting grafting orcross-linking of the polymer molecules contained in the particles of thefinished latex. When necessary after this treatment, the grafted orcross-linked latex may be stripped of residual volatiles and odor, as bypassing it through a stripper-deodorizer-concentrator circuit, which maybe the same circuit 1220-1216 isolated for this purpose as by openingvalves 1227 and 1229 and closing valves 1228 and 1230. Delivery of thetreated latex to storage 1233 is preferably effected after cooling in aheat-exchanger 1232, by appropriate adjustment of the valves 1227-1231.

b. The Polymer Material 1 The new process is applicable to thepreparation of latices from solvent solutions or dispersions of polymermaterials which are essentially solvent soluble or persable andessentially water insoluble, including if ural rubber and polymers ofethylenically unsaturated monomer material containing from 2 to 20carbon atoms, preferably from 2 to 10 carbon atoms. It is es peciallyapplicable to those elastomers and plastomers 12 which, with or withoutplasticiser, have the foregoing properties and properties adapting theirlatices for use as adhesives, binders, film forming materials, coatingmaterials, etc. Examples of such elastomers and plastomers, illustrativebut not restrictive of those to which the invention can be applied, areas follows: butyl rubber, chlorinated butyl rubber, polyisobutylene,polybutadiene, polyisoprene, polyethylene, polypropylene (including bothamorphous and/or crystalline polypropylene), ethylene-propylene polymer,ethylenepropylene-diene terpolymer, ethylene-vinylidene monomerinterpolymers (including ethylene-vinyl acetate copolymers),butadiene-ethylene copolymers, propylene-butene-l copolymers,butadiene-styrene copolymer, nitrile rubber (includingbutadieneacrylonitrile and butadiene-methacrylonitrile copolymers),natural rubber, hydrocarbon resins any of the foregoing polymers graftedwith polar or other polymer grafts, as for example, those set forth inBritish Patent No. 878,150 to Burke, published September 27, 1961, andsolvent soluble mixed plastomers and elastomers, e.g.butadiene-styrene-terpolymers with styrene copolymer resins includinggraft polymers thereof, as for example, those set forth in Hayes U.S.Pat. No. 2,802,808. Particularly included are those polymers which areprepared in essentially water immiscible organic liquid, or underessentially anhydrous conditions, from monomers unsaturated monomershaving 2 to 20 carbon atoms. 0. Compounding Ingredients 3, 3a, 1223a Thecompounding ingredients which are especially contemplated in the,present invention are. the solid, particulate, compounding ingredientswhich are insoluble in the solvents 6, namely: fillers, including rubberreinforing fillers, pigments, etc., which by the present invention maybeincorporated into the polymer composition particles of the latices,rather than merely in the water phases thereof. The solid particulatecompounding ingredients of this class comprise those set forth onv pages278 to 345 of Compounding Ingredients for Rubber 3rd Edition 1961published by Rubber World, New York, N.Y., herein incorporated byreference, and on pages 146 to 217 of British Compounding lngredientsfor Rubber by Brian J. Wilson (1958) published by W. Heffer & Sons,Ltd., Cambridge, England, herein incorporated by reference. Theseingredients thus include but are not limited to carbon black, talc,mica, lithopone, aluminum silicate, calcium silicate, silica, calciumcarbonate, calcium sulfate, asbestos, organic pigments, inorganicpigments, and insoluble organic fillers including vinylic fillers andvinylic pigments. The insoluble organic fillers are described in BritishPat. No. 799,043 to Burke published July 30, 1958 and in chapter 15entitled Reinforce- Emulsifiers capable of forming stable aqueousemulsions with polymers may be selected from the following sub-groups:

a. One or more anionic emulsifiers.

b. One or more cationic emulsifiers.

0. One or more nonionic emulsifiers.

d. Combinations of anionic and nonionic emulsifiers.

e. Combinations of cationic and nonionic emulsifiers.

The anionic, cationic and nonionic emulsifiers which are water solubleusually contain from 8 to 22 carbon atoms, when non-polymeric, but suchlimitation does not apply to those which are polymeric, where watersolubility or dispersability is the criterion. The polymeric emulsifiersare best employed in conjunction with non-polymer emulsifiers.

Emulsifiers of the anionic, cationic, and nonionic types including insome instances those in polymeric forms are set forth in Detergents andEmulsifiers 1967 Annual by John W. McCutcheon, published by John W.McCutcheon, lnc., Morristown, N..I., and especially those listed thereinunder the headings of emulsifiers suitable for emulsion polymerizationor suitable for the emulsification of polymer material, or suitable forthe emulsification of hydrocarbons including hydrocarbon waxes, may beused in practicing the present invention. The use of about 20 percent byweight of emulsifier material based on the polymer composition contentof the polymer-solvent cement in practically all instances suffices andin most instances 5 to 6 or less percent by weight of emulsifier basedon polymer composition content of the cement is sufficient, because thepresent process minimizes the amount of emulsifier required.

The anionic emulsifiers include but are not limited to emulsifiers whichare alkali metal salts of fatty acids, particularly hydrogenated fattyacids, rosin acids, disproportionated rosin acids, alkyl sulfates, aryland alkaryl sulfonates, and water soluble and dispersable emulsifiershaving the general formula: R(OCH CH ),,OSO;,X wherein R is analiphatic, aryl, alkaryl or cyclic radical, n is l to 9, and X is amonovalent alkali metal or ammonium radical.

Typical anionic emulsifiers are set forth in Table A.

TABLE A Typical Anionic Emulsifiers Acid or Salt Acid Radical Trade NameI. Potassium hydroabietic and Dresinate 731 dehydroabietic 2v Potassiumdisproportionated lndusoil JC-l 1B tall oil rosin 3. Sodium hydrogenatedArmeen HT tallow fatty acids 4. Sodium lauryl sulfate Sipex UB DupanolWAQ 5. Sodium tallow sulfate Conco Sulfate T 6. Ammonium mononaphthaleneLomar PWA sulfonic acid 7. Sodium dodecylbenzene Santomerse 85B sulfate8. Sodium polymerized alkyl Daxad l5 naphthalene Daxad 23 sulfonic acid9. Sodium alkyl aryl Nacconol 90F sulfonate Suframin OBS l0v Sodiumalkylnaphthalene Nekal BA-75 sulfonate l l. Sodium N-cyclohexyl-N-lgepon (N-42 palmitoyl-taurate l2. Sodium lauryl ether Sipon ES sulfate13. Sodium alkylaryl Triton W-3O polyether sulfate TABLE A-ContinuedTypical Anionic Emulsifiers Acid or Acid Radical Salt Trade Name sulfateester of nonylphenoxypoly (ethyleneoxy) ethanol sulfate ester ofnonylphenoxypoly (ethyleneoxy) ethanol naphthalene sulfonic acid dioctylester of sulfosuccinic acid saponified poly(methylvinylether/ maleicanhydride) saponified poly- (styrene/maleic anhydride) ]4. Sodium AlipalCO-433 l5. Ammonium Alipa] CO-436 16. Sodium Nacconol NRSF 17. SodiumAerosol OT 18. Sodium Gantex AN l 39 19. Sodium Lytron SMA-3000A Thecationic emulsifiers include, but are not limited to, the class ofemulsifiers which are acid salts of primary secondary, and tertiaryamines and the quaternary ammonium type emulsifiers. Typical cationicemulsifiers (used with acids to form water soluble salts when notquaternary ammonium compounds) are set forth in Table B.

TABLE B Typical Cationic Emulsifiers Emulsifier Base Trade Name 1.Cocoamine Armeen C 2. Sterylamine Armeen T 3. N-alkyl trimethylenediamines Duomeen C (alkyl groups derived from Duomeen T cocoanut, soya,and tallow fatty acids) 4. Primary fatty amine ethylene Priminox T-25oxide reaction products, e.g. RNH(CH CH ,O) -,H

5. Polyoxyethylated alkylamine Katapol PN-43O 6. Ethylene oxidecondensates Ethomeens with primary fatty amines 7. bis(2-hydroxyethyl)cocoamine Armox C/ 12W oxide 8. bis(2-hydroxyethyl)tallow amine Armox T/ 12 oxide Redicote Series e.g.Redicote E-4, E5, E-9, E-l2 and EN. Redicote El 1 Hyamine 1622 9. Amineand quaternary ammonium compounds suitable as asphalt emulsifiers IN BT(I$)2 2)3( 3)3 l l. di-isobutyl phenoxy ethoxy ethyl dimethyl ammoniumchloride 12. N-alkyl trimethylammonium Arquads chloride (alkyl coco orsteryl radical) l3. polyvinylpyrrolidine PVP TABLE Typical nonionicEmulsifiers Chemical Name Trade Name Nonylphenoxypoly( ethyleneoxylgepal CO-970,

ethanol having 8 to 10 ethylene oxide units The Polymeric Emulsifiersinclude the water dispersible polyelectrolytes set forth in Hedrick andMowrys US. Pat. No. 2,625,529 relating to Methods of Conditioning Soils.In said patent are listed a number of water-soluble polyelectrolytes andthese materials are defined as synthetic water soluble polyelectrolyteshaving a weight average molecular weight of at least 10,000 and having astructure derived by the polymerization of at least one monoolefiniccompound through the aliphatic unsaturated group and substantially freeof cross-linking." The present invention has shown that these syntheticwater soluble polyelectrolytes can be employed as emulsifiers for thepreparation of latices as herein set forth. The disclosedpolyelectrolytes of this patent are therefor incorporated herein byreference, it being noted however that the lower limit of molecularweight prescribed by the patentee does not apply, the applicablecriterion being that the materials are water soluble or waterdispersible emulsifiers Combinations of emulsifiers. The presentinvention has disclosed that by using certain combinations ofemulsifiers, it becomes possible to prepare a stable latex fromaliphatic hydrocarbon polymers dissolved in hydrocarbon solvents andeven in aromatic solvents, as is desirable under certain processingconditions. An effective emulsifier combination for aqueouslyemulsifying 100 parts by weight of a hydrocarbon rubber dissolved infrom about 300 to 600 parts of an aromatic hydrocarbon solvent such astoluene, may comprise 10 parts by weight of a nonionic emulsifier, e.g.polyoxyethylated octyl phenol such as Triton X-100, a trade mark productand one part by weight of an anionic emulsifier, e.g. sodium laurylsulfate.

Another effective emulsifier combination for 100 parts by weight ofhydrocarbon rubber dissolved in about 400 parts of aromatic solvent suchas toluene combines 3 parts by weight of the aryl anionic emulsifier,sodium salt of an alkaryl polyether sulfate e.g. Triton W-30 (a trademark product) and 3 parts by weight of the non-aryl anionic emulsifiersodium lauryl sulfate e.g. Dupanol WAQ (a trade mark product).

It has for some time been a desideratum in the art to have a stablehydrocarbon rubber latex suitable for combination with asphalt orasphalt emulsions, for road surfacing and roofing purposes, for example.Application Ser. No. 691,823 has disclosed that latices of hydrocarbonrubber such as butyl rubber, polyisobutylene, ethylene-propylene rubberor rubbery amorphous polypropylene, which are suitable for such use, canbe prepared by employing as emulsifier for the hydrocarbon solventsolution of the rubber a combination of emulsifiers in which one or morequaternary ammonium emulsifiers (e.g. the quaternary ammonium compoundssupplied under the Redicote trade mark), are

combined with one or more fatty acid amine or diamine type emulsifiersin the ratio of quaternary ammonium to fatty acid amine in the range offrom 1:5 to 5: I, notwithstanding that the quaternary ammoniumemulsifiers alone, for the most part, will not form stable aqueousemulsions with the above types of hydrocarbon polymers.

For example a stable aqueous latex is obtained from hydrocarbon rubbere.g. butyl rubber or ethylenepropylene rubber, dissolved in an aliphaticor even an aromatic solvent, e.g. hexane, benzene, toluene and/or thezylenes, with the aid of a mixture of the emulsifiers selected fromsubgroups (a) and (b) in the ratio of 0.5:5 to 5:0.5 parts by weight,said mixture being employed in the amount of2 to 10 parts by weightbased on the polymer, and said sub-groups (a) and (b) being representedby formulae l and II respectively:

CH CH wherein R and R are slected from the alkyl radicals having from 8to 22 carbon atoms and X is an acid anion, preferably the alkyl radicalsbeing those derived from cocoanut oil and/or tallow fatty acids.

The quantity of emulsifier employed in this invention is in the range of2 to 20 percent by weight and preferably 5 to 10 percent by weight basedon the high polymer composition; and if desired, small additions ofelectrolyte may be made to the latex or in preparing the course or fineemulsion, as, for example, in accordance with the practices referred toin US. Pat. Nos. 2,955,094 issued Oct. 4, 1960 and 3,222,311, issuedDec. 4, 1965, to Esso Research and Engineering Company, as assignee ofR. S. Brodkey et al, and A. L. Miller et al. Alkali metal acid phosphatesalts are suitable for this purpose, and are also useful in connectionwith the use of the addituent 24d (FIG. 1) as above described, forreducing the quantity of said addituent required. e. Monomer Materials4b, 24b, 1224b The ethylenically unsaturated monomer material employableherein is selected from the class consisting of:

i. the mono-ethylenically unsaturated aromatic hydrocarbon monomerscontaining from 8 to 18 carbon atoms,

ii. the conjugated diene hydrocarbon monomers containing not more than12 carbon atoms,

iii. the non-conjugated diene hydrocarbon monomers containing not morethan 18 carbon atoms,

iv. the mono-ethylenically unsaturated monomers containing polar groupsand having not more than 18 carbon atoms, and

v. the non-conjugated diene and triene monomers containing polar groupsand having not more than 22 carbon atoms,

the polar groups of (iv) and (v) being selected from the classconsisting of carboxyl, hydroxyl, carbonyl, ester,

ether, nitrile, amine, quaternary ammonium, amide, triazine, and halogengroups,.

Examples of the mono-ethylenically unsaturated aromatic hydrocarbonmonomers of group (1) include vinyl, vinylidene and allyl aromaticmonomers such as styrene, the vinyl toluenes, the methyl styrenes, theethyl styrenes, the propyl styrenes, the vinyl biphenyls, the vinylnaphthalenes, and (1 and/or [3 alkyl substituted vinyl aromatics such asa -methyl styrene, isopropenyl biphenyl, and the like.

Examples of the conjugated diene monomers of group (ii) includehydrocarbon conjugated dienes such as butadiene- 1,3,isoprene,2,3-dimethylbutadiene-l ,4, piperylene, pentadiene-l,3,2-phenyl-butadienel ,3, and the like; the polar conjugated dienessuch as land 2-cyano-butadiene-l,3, 2-chlorobutadiene-l,3 and the like.

Examples of the non-conjugated diene hydrocarbon monomers of group (iii)include: the dialkene aryl compounds and derivatives including thedivinyl-, divinylidene and diallyl aryl compounds, such as divinylbenzenes, divinyl toluenes, divinylxylenes, divinyl ethyl benzenes,divinyl biphenyls and divinylnaphthalenes, divinyl methylnaphthalenes,and the like.

Examples of the mono-ethylenically unsaturated monomers of group (iv)which have polar groups selected from the class consisting of carboxyl,hydroxyl, ester, carbonyl, ether, nitrile, amine, quaternary ammonium,amide, triazine, and halogen groups include:

2. among the carboxyl group containing monomers the olefinic acids andtheir derivatives such as acrylic acid and the alpha and/or beta alkyl,aryl, and alkaryl substituted acrylic acides such as the methyl, ethyl,propyl, butyl, isobutyl, phenyl, tolyl and the like alpha and/or betasubstituted acrylic acids including a'methacrylic acid, a-ethacrylicacid, a-propylacrylic acid, a-butylacrylic acid and a-phenylacrylicacid, and the like, and further including the oxy, hydroxy and halogen,including the fluoro, chloro, and bromo derivatives of these olefinicacids and substituted olefinic acids and the like; the half alkenylesters of saturated dicarboxylic acids such as the vinyl, vinylidene andallyl half ester of such saturated dicarboxylic acids as oxalic,malonic, succinic, glutaric, adipic, tartaric, citric, phthalic and thelike;

b. among the hydroxyl groups containing monomers the partial esters ofpolyols and olefinic acids such as the mono-glycol esters, themono-glycerol esters, the monopropylene glycol esters of olefinic acidsincluding acrylic, methacrylic, ethacrylic and the like;

c. among the ester group containing monomers esters of olefinic acidsincluding a and B substituted olefinic acids and including alkyl,alkenyl, aryl, aralkyl esters such as the methyl, ethyl, propyl, butyl,isobutyl, pentyl, hexyl, cyclohexyl, phenyl esters of acrylic,methacrylic, ethacrylic, and the like; and including theoz-haloacrylates such as methyl a-chloroacrylate, propyla-chloroacrylate and the like; the

esters of olefinic alcohols with saturated acids, such as allyl,methallyl, crotyl, l-chloroallyl, 2-chloroallyl, cinnamyl, vinyl,methylvinyl, l-phenylallyl, butenyl and the like esters of saturatedaliphatic and aromatic monobasic acids as vinyl and allyl acetate,isopropenyl acetate, vinyl formate, vinyl- Z-ethyl hexoate, methyl vinylacetate, vinyl and allyl propionate, nbutyrate and isopropenylpropionate, isopropenyl butyrate, vinyl and allyl benzoate, and thelike; the dialkyl esters of olefinic dicarboxylic acids such as thedialkyl esters and mixed dialkyl esters from such alkyls as methyl,ethyl, propyl, and the like through C of the olefinic dicarboxylic acidsincluding maleic, citraconic, itaconic, muconic, glutaconic, fumaric andderivatives of these esters such as diethylchloromaleate and the like;

d. among the carbonyl group containing monomers the olefinic aldehydessuch as acrolein, methacrolein, crotonaldehyde and the like; the alkenylketones such as methyl vinyl ketone, isopropenyl methyl ketone, allylmethyl ketone, mesityl oxide, allyl phenyl ketone and the like;

e. among the ether group containing monomers the olefinic ethers such asvinyl ethyl ether, vinyl butyl ether, vinyl cyclohexyl ether, vinylphenyl ether, vinyl benzyl ether, methyl isopropenyl ether, allyl ethylether, methallyl ethyl ether, chloroallyl ethyl ether and the like;

f. among the nitrile group containing monomers the olefinic nitrilessuch as acrylonitrile, methacrylonitrile, ethacrylonitrile,chloroacrylonitrile and the like;

g. among the amine group containing monomers the olefinic amines, suchas N,N-dimethyl allyl amine, allylamine, N,N-diethyl, dipropyl, dibutyl,diisobutyl, diphenyl and similar allylamines and N-allyl morpholine,N-allyl-pyridine, N-allylethyleneimine and the like; the amino olefinicethers such as the amino vinyl ethers including aminoethylvinyl ether,N-ethylaminoethylvinyl ether, amino propylvinyl ether,N-methylaminoethylvinyl ether, N,N-diethylaminoethylvinyl ether and thelike; nitro* gen containing esters of olefinic acids such asaminocyclohexyl methacrylate, triethanolamine monomethacrylate, B-piperidyl-N-ethyl methacrylate ,8 -morpholine-N-ethyl methacrylate," N-methacrylyl morpholine, N-methacrylyl thiomorpholine, N-emthacrylylpiperidines, N-acrylyl morpholine, N-acrylyl thiomorpholine, N-acrylylpiperidine and the like; the N-vinyl monomers such as N vinylpyrrole,N-vinyl carbazole, N-Vinylindole, N- vinyl succinimide and the like;N-vinyl lactams such as N-vinyl caprolactam, N-vinyl butyrolactum andthe like; the acylamino substituted acrylic and aand B-acrylic acidesters such as the methyl, ethyl, propyl and the like alkyl esters ofa-acetoaminoacrylate, a-N-butylaminoacrylate and the like; the vinylpyridines such as 2-vinylpyridine, 3-vinylpyridine, 4- vinylpyridine,2-vinyl-5-ethylpyridine, 2-methyl-5- vinylpyridine and the other ethyland methyl isomers of vinylpyridine and the like;

h. among the quaternary ammonium group containing monomers thequaternary ammonium monomers which comprisemethacryloxyethyltrimethylammonium sulfate and various quaternizingreaction products of quaternizing agents such as alkyl halides, alkylsulfonates, alkyl phosphates and the like (e.g.

methyl bromide and toluene sulfonate) with tertiary amine monomers suchas ,B-dimethylaminoethyl methacrylate, methyl a-diethyl aminoacrylate,methyl a-(N-methylanilino)-acrylate, methyl a-dibenzylaminoacrylate,methyl a-distearylamino acrylate and the like;

i. among the amide group containing monomers the amides and substitutedamides of acrylic acid and a and ,B-substituted acrylic acids such asacrylamide, methacrylamide, ethacrylamide, N-methacrylamide,N-methlmethacrylamide, N,N-bis (hydroxyethyl) acrylamide,N,N-diethylacrylamide, N,N-ethylmethylacrylamide and other monoand di- Nsubstituted unsaturated acid amides where the substituent is C, to Calkyl alkoxy, haloalkyl and the like; the fluorosubstituted amides ofolefinic acids such as N-(2,2,3-trifluoroethyl) acrylamide,methacrylamide, N-(2,2-difluoroethyl acrylamide and methacrylamide;

j. among the triazine group containing monomers the monoolefinictriazine monomers including triazine monomers in which one of thecarbons of the triazine ring is attached to a vinyl, allyl, methallyl,crotyl, l-chloroallyl, 2-chlorallyl, cinnamyl, butenyl radical or thelike and the other carbons of the triazine are attached to cyano, halo(F, Cl, Br), amino, alkoxy, cycloaliphatic (e.g. cyclopentyl,cyclohexyl, etc.), aromatic-substituent (e.g. phenyl, biphenyl,naphthyl, etc.), alkylaryl (e.g. tolyl, xylyl, ethylphenyl.) halogenatedaromatic and the like; the N-vinyl and allyl guanidines and includingallyl melamine, allyl isomelamine and the like; the N-vinyl-N-alkylguanidines such as N-vinyl-N-n-butylguanidine, N-vinyl-N-benzylguanidine, acryloguanamine, methacryloguanamine and the like; and

k. among the halogen group containing monomers the olifinic halides,such as vinyl fluoride, vinyl chloride, vinyl bromide, vinylidenefluoride, vinylidene chloride, allyl fluoride, allyl chloride,a-methallyl fluoride, a-methallyl chloride, a-ethallyl fluoride orchloride or bromide, tetrafluoroethylene, trifluorochloroethylene,dichloridifluoroethylene, trichlorofluoroethylene, perfluoropropylene,l-phenyl-l,2 difluoroethylene, trichloroethylene and the like; olefinicacid esters of fluoro alcohols such as the a-trifluoromethyl acrylicacid esters such as the methyl or ethyl ester or the ester ofprefluoroethanol or the partially fluorinated alcohols, that is thefluoroalkanols such as octafluoropentanol and the like; and halogensubstituted aryl olefines such as the halo (F, Cl, Br) substituentsincluding the mono, di, tri, and tetra chloro styrenes, thefluorostyrenes, the chlorovinyl toluenes, the fluorovinyl toluenes, thecyano styrenes and the like monomers.

Examples of the non-conjugated diene and triene monomers of group (v)containing polar groups from the class consisting of carboxyl, hydroxyl,ester, carbonyl, ether, nitrile, amine, quarternary ammonium, amide,triazine and halogen groups include:

a, b, c among the carboxyl group, hydroxy group, and ester groupcontaining monomers the olefinic dicarboxylic acids and their acidanhydrides and the half alkyl, aryl or alkaryl esters of olefinicdicarboxylic acids such as maleic, citraconic, itaconic, mesaconic,fumaric, muconic and similar acids including their acid anhydrides suchas maleic anhydride and the like and the alkyl and aryl half esters ofthese olefinic dicarboxylic acids like monoethyl fumarate, monomethylitaconate and the halo-derivatives of these such as chloromaleicanhydride; the olefinic nitrile and other polymerizable olefinicnitriles and these can be polymerized and can then have their cyanogroups converted to carboxyl groups by saponification with a strongalkali such as sodium hydroxide or potassium hydroxide; monomers havinga plurality of polymerizable unsaturated carbon-to-carbon bonds at leasttwo of which are nonconjugated, including the polyunsaturated esters ofolefinic alcohols and unsaturated mono-carboxylic acids such as thevinyl, vinylidene, and allyl, methallyl, crotyl, l-chloroallyl,2-chloroallyl, cinnamyl, methyl vinyl, l-phenyl allyl, butenyl esters ofunsaturated monocarboxylic acids such as vinyl acrylate, allyl acrylate,the vinyl and allyl esters of a and B substituted acrylates such asvinyl methacrylate, vinyl crotonate, vinyl ethacrylate, allylmethacrylate, allyl ethacrylate, vinyl a-chloroacrylate, allyla-hydroxyethyl acrylate, and the like; the polyunsaturated esters ofsaturated dicarboxylic and polycarboxylic acids such as the vinyl,vinylidene, allyl, methallyl, crotyl, l-chloroallyl, 2- chloroallyl,cinnamyl, methyl vinyl, l-phenyl allyl, butenyl esters and mixed estersof such dicarboxylic acids as oxalic, malonic, succinic, glutaric,adipic, tartaric, citric, and the like including such monomers asdiallyl oxylate, diallyl sebacate, diallyl adipate, diallyl succinate,diallyl malonate, triallyl citrate and the like; polyunsaturated estersof unsaturated polycarboxylic acids, such as the vinyl, vinylidene,allyl, ethallyl, crotyl, 1- chloroallyl, 2-chloroallyl, cinnamyl, methylvinyl, lphenyl allyl, butenyl esters and mixed esters of the unsaturatedpolycarboxylic acids such as maleic, citraconic itaconic, mesaconic,fumaric, muconic, chloromaleic, aconitic and the like including suchmonomers as diallyl fumarate, diallyl homophthalate, diallyl itaconate,diallyl ester of muconic acid, diallyl maleate, diallyl phthalate,diallyl isophthalate, diallyl terephthalate, triallyl aconitate and thelike; polyhydroxy esters of unsaturated acids such as the glycol esters,glycol ether esters, the trihydroxy-, tetrahydroxy-, pentahydroxy-,hexahydroxyesters including the glycerides, the pentoses, the hexosesesters of acrylic acid and a and B-substituted acrylic acid such asethylene diacrylate, ethylene dimethacrylate, propylene dimethacrylate,glycerol dimethacrylate, glyceryl trimethacrylate, tetramethylenediacrylate and dimethylate, tetraethylene glycol dimethacrylate andincluding the pentose and hexose diesters and triesters of acrylic acidand the aand B-substituted acrylic acids, such as pentosedimethacrylate, hexose triacrylate and the like; unsaturated half estersof unsaturated dicarboxylic acids including the vinyl, vinylidene andallyl half esters of the unsaturated dicarboxylic acids such as maleic,citraconic, itaconic, mesaconic, fumaric, muconic, chloromaleic,aconitic and the like, such as monoallyl maleic acid, mono-vinylitaconic acid and the like; reaction products of alkenyl halide with apolyhydric alcohol such as allyl chloride, allyl bromide, methallylchloride, .nethallyl bromide, crotyl chloride reacted with suchlnzoiiols as butane triols, erythritols, saccharides, polysaccharidesand other sugars such as glucose, sucrose, maltose, arabitol, mannitol,starches and the like; and other monomers containing a carboxyl groupand a plurality of unsaturated double bonds;

d. among the carbonyl group containing monomers polyunsaturated ketonessuch as divinyl ketone, diallyl ketone, and the like;

e. among the ether group containing monomers polyunsaturated ethers suchas divinyl ether, diallyl ether, divinyl carbitol, divinyl ether ofdiethylene glycol, diallyl and triallyl glycerol ether, diallyl 1,2-propanediol ether, diallyl 3-butene-l ,2,3-propanetriol, diallyl andtriallyl ethers of l-phenyl-l,2,3- propanetriol, diallyl-l,S-naphthalenediamethyol ether, and the like;

f. among the nitrile group containing monomers the allyl ester ofa-cyanoacrylate, and the like;

g. among the amine group containing monomers diallyl amine, triallylamine, and the like;

h. among the quaternary ammonium group containing monomers tetra allylammonium chloride, methyl-triallyl ammonium bromide,methyl-benzyl-diallyl ammonium bromide, reaction products of maleicanhydride, and triallylamine quaternized with allyl chloride, and thelike;

i. among the amide group containing monomers polyunsaturated acid amidessuch as N,N-diallyl acrylamide, N,N-diallyl methacrylamide,N,N-methylene bisacrylamide and the like;

j. among the triazine group containing monomers polyunsaturatedtriazines, the diallyl cyanurate, N,N- diallyl melamine,2,4-diallyloxy-6-amino-5-triazine, the diand trivinyl cyanurates andderivatives of these and the like; and

k. among the halogen group containing monomers the halo (F, Cl, Br)mono-, di and polysubstituted divinylbenzenes, divinyl naphthalenes,divinyl biphenyl oxides, divinyl tolunes, and the like.

Further examples of monomers of the class and subclasses defined, whichare employable herein and are set forth in Burke, et al. U.S. Pat. No.3,144,426, columns to 7, and are herein incorporated by reference.

The foregoing monomers include monomers which are predominantly watersoluble as well as monomers which are predominantly oil soluble, andwhen it is desired to produce an interpolymer latex, it is preferred toemploy monomers predominantly soluble in the polymer phase of the latexand in any event to effect the polymerization with the aid ofpredominantly oil soluble polymerization catalyst or a redox system atleast a compound portion of which is predominantly soluble in themonomer polymer phase. The oil and water solubilities of monomer andcatalyst materials are known to or readily determinable by those skilledin the art.

f. Free-Radical Generating Polymerization Catalysts 4a, 24, 122411.

The free-radical generating catalysts and catalyst systems useful in therange of 0.8 to 20 parts per 100 parts of added monomer materialsemployed in certain embodiments of the present invention constitute awellknown class which includes: the inorganic peroxides such as hydrogenperoxide and the like; the various organic peroxy catalysts, such as thedialkyl peroxides, e.g. diethyl peroxide, diisopropyl peroxide, dilaurylperoxide, 'dioleyl peroxide, distearyl peroxide, di- (tertiary-butyl)peroxide; di-(tertiary amyl) peroxide, dicumyl peroxide and the like;the alkyl hydrogen peroxides such as tertiary butyl hydroperoxide,tertiary amyl hydroperoxide, cumene hydroperoxide, tetralinhydroperoxide, and diisopropyl benzene hydroperoxide and the like; thesymmetrical diacyl peroxides, for instance acetyl peroxide, propionylperoxide, lauroyl peroxide, stearoyl peroxide, malonyl peroxide,succinoyl peroxide, phthaloyl peroxide, benzoyl peroxide, ketoneperoxide such as methylethyl ketone peroxide, cyclohexanone peroxide,and the like; the fatty oil acid peroxides, such as cocoanut oil acidperoxides and the like; the unsymmetrical or mixed diacyl peroxides,such as acetyl benzoyl peroxide, propionyl benzoyl peroxide and thelike; the azo compounds such as 2-azobis (isobutyronitrile), 2-azobis(2-methylbutyronitrile), l-azobis (l-cyclohexancarbonitrile) and thelike, and other free radical generating catalysts employable in emulsionpolymerization, such as peroxy-catalyst compounds in combination with areducing compound such as an amine, e.g. triethylene tetramine ortetraethylene pentamine, with or without metallic ion combination, e.g.,ferrous ions, which systems are referred to as redox free-radicalgenerating catalyst systems, which latter are further exemplified in thetreatise Emulsion Polymerization by F. A. Bovey, et al., 1955Interscience Publishers, lnc., New York, N.Y. at pages 7l-93, hereinincorporated by reference. g. Cross-linking Agents 240, 12240 Thecross-linking agents useful, in the range of 0.1 to 20 parts per partsof polymer content of the latex by weight, for effecting thecross-linking employed in particular embodiments of the presentinvention, also form a well-known class of materials which includes:elemental sulfur, selenium and tellurium, and compounds containing theseelements, usually in their lower valence states or covalance states, andother polyfunctional free radical generating catalysts. Compounds whichliberate sulfur, selenium or tellurium during irradiation or during heataging (100 to 200 C.) are useful. Polymers containing sulfur, seleniumor tellurium and/or monomers capable of forming such polymers are alsouseful. Conventional rubber vulcanizing agents and vulcanizingaccelerators are particularly adapted to this application. Specificcompounds of the class are: The mercapto thiazoles, such as2-mercaptobenzothioz0le and its salts, for example its zinc salt,thiuram sulfides, such as tetraethylthiuram monosulfide andtetrabutylthiuram monosulfide; guanidines, thiourea, substitutedthioureas, thiocarbanilides, substituted thiocarbanilides such aso-dimethylthiocarbanilide and its isomers and alkyl homologs; zincdialkyl dithiocarbamates such as zinc dimethyl dithiocarbamate, zincdiethyldithiocarbamate, zinc dibutyl dithiocarbamate, and zinc dibenzyldithiocarbamate or accelerators containing these materials, thiuramssuch as tetramethylthiuram disulfide, tetraethylthiuram disulfide, andother tetra substituted thiuram disulfides; selenium dialkyldithiocarbmates such as selenium diethyldiethiocarbamate;2-benzothiazyl-N,N-diethylthiocarbamyl sulfide; sodium or potassiumdimethyldithiocarbamate; xanthates such as dibutyl zanthogen disulfideand Naugatuck Chemicals CPB and ZBX; alkyl phenol sulfides;bis(dimethylthiocarbamyl) disulfide, dipentamethylene tetrasulfide; andsulfur containing polymers such as Thiokol VA-3,4,4-dithiomorpholine anddisulfides such as benzothiazyl disulfide. In fact, any compound inwhich sulfur, selenium or tellurium is attached only to an atom ofcarbon, hydrogen, nitrogen or to another sulfur, selenium or telluriumatom, as the case may be, may be suitable.

Also included in the class are the sulfonyl hydrazides and disulfonylhydrazides. The latter are particularly useful since they contain twowidely separated sulfurbearing moieties capable of forming sulfurcross-links or free radical derived cross-linkages (as a result ofthermal loss of nitrogen). Blowing agents such as p,p'- oxybis (benzenesulfonyl hydride), p,p-diphenyl bis(- sulfonyl hydrazide) andm-benzene-bis(sulfonyl hydrazide) are examples of additives which canalso be employed as cross-linking agents.

Included in the class are the cross-linking azo compounds, e.g.di-cyano-azo-butane; and the like.

Included in the class are also the peroxy compounds such asbis(a-,a-dimethyl-dicumy) peroxide (dicumyl peroxide), l,3-bis( a-,t.butylperoxypropyl) benzene, 2,5-bis(t.butylperoxy)-2,5-dimethylhexane,2,5- dimethyl-2,5-di(t.-butylperoxy)hexyne-3,di(oz-,adimethyl-p-chlorobenzyl)peroxide, di(a-, a-dimethyl-2,4-dichlorobenzyl) peroxide, di(a-, a-dimethylnaphthyl)peroxide and thelike.

Further included in the class are combinations of the above said peroxycompounds and the above said sulfur, selenium and tellurium compounds.

h. Latex Destabilizing Agents 24d The latex destabilizing agentsemployed in certain embodiments of the present invention are latexcoagulating agents employed in insufficient quantity to coagulate thelatex. Such destabilizing agents thus are selected from the classconsisting of (i) which are sufficiently low boiling and weakly acidicto enable their removal from the latex or (ii) which are desirableadditives to the latex, namely, (a) acetic acid, ammonium carbonic acidsalts, namely ammonium carbonate and ammonium bicarbonate, and (b)phosphoric acid, al-

kali metal acidic salts of phosphoric acid, and ammonium acidic salts ofphosphoric acid; and the less preferred destabilizer acidic additiveswhich can be employed without the advantages of (i) and (ii) namely(iii) sulfuric acid, hydrochloric acid, and alkali metal acidic salts ofsulfuric acid and phosphoric acid and ammonium salts of sulfuric acidand phosphoric acid and the like.

The particular quantity of destabilizing agent to be employed variessomewhat with the nature and condition of the latex, but is readilydetermined in any particular case by measuring the quantity ofdestabilizer just sufficient to coagulate a sample of the latex and thenemploying a lesser quantity of destabilizer, which, while not criticalas to outside limit, is preferably from about one-half to two-thirds ofthe determined coagulating quantity.

i. Ionizing Radiation The ionizing radiation employed in certainembodiments of the present invention is of a type known to those skilledin the art, viz: it is radiation with sufficient energy to remove anelectron from an atom, forming an ion pair; this requires an energy ofabout 32 electron volts (ev.) for each ion pair formed. This radiationhas sufficient energy to non-selectively break chemical bonds; thus, inround numbers radiation with energy of 50 electron volts (ev.) and aboveis effective for the process of this invention. Such ionizing radiationis generally classed in two types; high energy particle radiation, andionizing electromagnetic radiation. The effect produced by these twotypes of radiation is similar, the essential requisite being that theincident photons have sufficient energy to break chemical bonds andgenerate free radicals.

The preferred radiation for the practice of the said embodiments of thisinvention is high energy ionizing radiation, and has an energyequivalent to at least 0.1 million electron volt (mev.). Higher energiesare even more effective; there is no known upper limit, except thatimposed by available equipment and the product stability.

When irradiation is employed in the present invention, it is preferablyeffected at about atmospheric pressure and at temperatures between about5 and C., a temperature of about 2565 C. being preferred.

As is well known in the irradiation grafting of solid substrates, theoptimum dose of irradiation varies with the particular materialsconcerned, a dose of about 5,000 rads (0.005 mrad) being required forsignificant grafting. Dosages and dosage rates may be selected betweenthe limits which with given latices and under the conditions concernedare sufficient to not require excessive time of treatment and those notso high as to cause excessive rise of temperature, eg above 95 C., orexcessive decomposition of materials concerned. Such limits are wellunderstood by those skilled in the irradiation art, and are readilydetermined for particular materials by simple tests as above indicated.

j. Equipment l-Iomogenizers While the invention in its broader aspect isnot limited to any particular homogenizer, the invention has disclosedthat certain types of homogenizer described in Mould, IL US. Pat. No.3,l95,867* and Hager US Pat. No. 3,l94,540* as suitable for lowviscosity materials such as milk, oil, fruit slurries, etc., can beemployed effectively as an ultra-disperser of aqueous emulsions ofhighly viscous solutions of polymer compositions, especially whenconnected in tandem, and/or for recycle, and in particular that acombination of such Mould type homogenizers followed by a resilientlyrestricted orifice type high pressure homogenizer (1,000 to 10,000p.s.i.) e.g. of the Gaulin type (see Gaulin US. Pat. Nos. 753,792* and756,953* as available from Manton-Gaulin Mfg. Co., Inc., as model'K24-3BS but provided with a 75 horsepower motor,

provides an aqueous emulsion of solvent/polymer cement yielding a latexhaving latex particles of an aver age diameter near the upper end of thecolloidal size range suitable for high solids polymer latices, and ofrelatively narrow particle size distribution.

(* Herein incorporated by reference.)

In FIG. 2 there is shown an arrangement of such Mould type and Gaulintype homogenizers to constitute a preferred cemement emulsifyingequipment. This arrangement is provided with optional facilitiesselectively employable by means of valves for continuous or batchoperation, for single unit or tandem unit operation, and for selectivecomplete or partial recycle in each mode of operation, and it will ofcourse be understood that where certain of these optional facilities arenot desired they may be omitted without departing from the invention.

In this FIG. 2 arrangement the solvent and polymer dispersion 107 andthe water and emulsifier solution 108 are adjusted in temperature byheat exchangers 110A and passed to the course emulsion mixer equipment.For batch operation, as shown, this equipment may be in the form of ahold tank 110 provided with an agitator. For continuous operation, asshown, it may be in the form of in-line mixing equipment 110B. Theinline mixer equipment 110B may also be employed to premix the materialsbeing delivered to tank 110 for batch operation. The coarse emulsion inbatch operation is passed from tank 110 under gravity head and/orpressure head contributed by pump 110C to the ultradispersing equipment112 and/or 112A and/or 1128, or for continuous operation may be passedto the latter directly from the in-line mixer equipment 1108, and underthe head developed thereby augmented, if desired, by the head developedby pump 110C. The coarse emulsion under pressure as aforesaid may bepassed through any one of more of the ultradispersing equipments112-1128 and may be recycled therethrough either directly, or by way ofthe coarse emulsion tank 110. When the preparation of the emulsion ofprecursor latex sized particles has been completed this intermediateproduct may be delivered to storage 113, preferably being cooled bymeans of a cooler 113F to assure maintenance of the emulsion even withminimum quantities of emulsifying agent present. As is indicated in FIG.2, effective results have been attained by repeatedly passing the coarseemulsion through an equipment 112 of the perferated stator type shown inMould, .lr. US. Pat. No. 3,195,967, and then through one or moreequipments 112A and/or 1128 in tandem with, and similar to, equipment112 but provided with a slotted stator of the type illustrated in FIGS.and 7 of l-Iager US. Pat. No. 3,194,540, with recycling from equipment112A to the tank 110 and then by gravity head through equipments 112 and112A, about a half dozen to a dozen times before delivery of theresulting product to the storage tank 113. During recycling, especiallywith sensitive emulsion prepared with a minimum of emulsifying agent, itis desirable to cool the emulsion which has been heated by working inthe ultradispersing apparatus, by means of a heat exchanger in therecycle line, as at 112C.

As is further shown in FIG. 2, the presently most preferred arrangementfor producing a cement of high polymer content without excessiverecycling in the Moulds equipment 112-112B, employs a high pressureresiliently restricted orifice type homogenizer 113D, 113E as abovedescribed to which the emulsion efiluent from the homogenizers 112-112Bis fed after heating to temperature e.g. l40160F by the heat of 113A.the Gaulin type homogenizer comprises the pump 113D which is a plungerpump that develops from 1,000 to 10,000 p.s.i. depending on theresilient load applied to the valve head means resiliently restrictingthe emulsifying orifice or valve-opening means of the device. This loadcan be adjusted in the commercial devices by means of a hand wheel,shown at the entrance end of the homogenizer 113E. The output from theunit 113E may be delivered to cooler 113F and thence to storage 113, ormay be delivered to storage tank 113G when recycled through thehomogenizer circuit Il3D-l13F is desired.

Stripping Mixer The stripping mixer 14 (FIG. 1) which disperses theaqueous emulsion of precursor latex sized solvent- /polymer dropletsinto the gaseous stream of steam is preferably of the type illustratedin FIG. 4, consisting of a conduit section 114, which may betransparent, which has supported centrally thereof a torpedo shaped orfid-shaped member 114A for producing a restricted or venturi-effectpassage 114B thereabout. The initial continuous phase of steam isadmitted as at 114C to flow through the passage 114B and produce an areaof high velocity and low static head thereat. The aqueous emulsion ofsolvent/polymer solution is introduced into the central body 114A as byway of the tube 114D upon which it is supported, and issues into the gasstream via a narrow slot 114E extending peripherally of the body 114A atthe region of greatest pressure reduction in the space 114B. Theauxiliary flows of steam are introduced as above described, at 1 14F and114G. The outlet of the section 114 connects to the vacuum equipment byway of the segregator and collector devices, as exemplified in FIGS. 3and 5, and the vacuum in the chamber 114 is such that the temperaturesattained do not exceed those at which the emulsion and latex are stable.The heat for vaporization of the solvent from the solvent/polymersolution is for the most part derived from the condensation of thesteam, and the flowing stream of stream and organic vapor carrying theresulting suspended latex droplets is in the natureof an aerosol,exhibits no foaming in the tube 114, and does not coat or foul the tube114. As is illustrated in FIG. 3, the aqueous emulsion ofsolvent/polymer solution is usually supplied to the mixer 114 underpressure, as by a pump 114H.

Elongated Path Progressive Segregating Means The stripping operations ofthe process in certain embodiments thereof may be practiced with anysuitable segregating means which provides an elongated path forturbulent or tortuous flow of the latex droplets constituting thediscontinuous phase together with the vapor stream constituting thefluid driving continuous phase, with a decrease in pressure as the twophases progress along the path, the turbulance being such as togradually coalesce the aerosol sized latex droplets into droplets of asize that can be separated from the gaseous stream carrying the same,while avoiding excessive foaming and while maintaining the temperatureof the two phases within the limited range for stability of theoil-in-water emulsion concerned. While a number of types of apparatusare adaptable for the purposes, an effective and possibly the mostcompact arrangement is afforded by a heat exchanger of the corrugatedplate type, arranged with the space between adjacent pairs of platesconnected in series to afford the elongated tortuous path terminating inan evacuated separator or collector device. Such arrangement isillustrated as alternate in FIG. 3, wherein the aerosol like suspensionfrom the mixer 114 is delivered through the plate type segregator 215 tothe separator or collector 216, all under partial vacuum.

High-G Latex Droplet Segregating Means An alternative and sometimespreferred form of segregating means is that illustrated at 115 in FIG.3, and consists of a centrifugal pump having a pump rotor, pump chamber,and inlet and outlet means of the type shown in Freed et al., US. Pat.No. 3,324,798*. The two phases of the aerosol-like suspension of latexdroplets in the solvent vapor stream are passed through the centrifugalpump 115, which delivers from an area of relatively high pressure to anarea of relatively low pressure (adjustable by valve means 1141-1 and115A) and the latex droplets coalesce against the rotating andstationary surfaces of the pump and travel outwardly therealong, theinclination of the surfaces determining what part of the centrifugalforce developed tends to move the coalescing latex latex along the pumpwalls and what part thereof tends to press the coalescing latex againstthe pump walls for aiding in preventing foaming.

(*Herein incorporated by reference.)

Separating, Condensing, and Evacuating Apparatus As will be apparent tothose skilled in the art the invention in its broader aspects is notdependent on the use of any particular type of separating, condensingand evacuating apparatus. Conveniently, when stripping azeotropingsolvent, as a separator or collector 16 may be used a verticalcylindrical receiver, with a downwardly tapering bottom leading to adischarge opening connected to a positive displacement pump for removalof separated latex therefrom without breaking the vacuum, with atangential side opening for passage of the two flows thereinto, and witha top opening for the discharge of the continuous phase to thecondensing equipment. The latter conveniently may comprise twocondensers, one for non-azeotroped water, and the other operating at alower temperature for azeotrope of water and solvent. The evacuatingapparatus conveniently may comprise a steam jet evacuation equipmentconnected to draw non-condensed material from the condenser equipment,or a vacuum pump.

In the form shown in FIGS. 3, 4 and 6, the collector 216 generallyresembled a cyclone collector into which the gaseous flow and any latexdroplets carried thereby are discharged tangentially from the inlet215H, and guided along the walls by appropriate internal baffling, e.g.the drop tube 216D, so that the liquid collects on the walls and flowsto the bottom outlet 216C, while the gas passes to the top outlet by wayof the passage afforded by the central drop tube, or equivalent bafflingmeans, 216D to the condensor/vacuum system. Pump means 216E delivers thelatex from the outlet 216C through the outlet valve 216B and, dependingon pump and valve setting, wholly or partly via the recycle lines 2166,216L. Valve 216M can be a pressure opened relief valve for maintaining adelivery pressure at the output of pump 216E while recycling all thelatex not delivered by pump 324 or otherwise removed. As beforementioned, the walls of the collector 216 are preferably covered by aflow of latex from a distributor 216A, which provision facilitates thecollection of the latex droplets delivered by the gas stream whileminimizing foaming.

As is also shown in FIG. 3, the freshly stripped latex, preferablywithout removal of its residual solvent, is delivered by pump 324a viaheat exchangers 325 and/or 325a and/or storage hold tank 324 to meansfor modifying the latex which may be used separately or in combinationin the arrangement shown. The modifying homogenizer 326, as explained inconnection with element 26, FIG. 1, effects the modifications of thelatex there set forth, the concentrating circuit 1216-1220 correspondswith the concentrating circuit 31-32 of FIG. 1; and the modifyingequipment 1224-1233 has been described above.

As specific illustration of the practice of the invention by theprocedures above described reference may be had to the followingexamples which are illustrative, but not restrictive, of the invention.

EXAMPLE 1 Preparation of Butyl Rubber Latex.

The coarse emulsion for this example is formulated as follows:

To a sigma blade mixer is added 800 lbs. of butyl rubber and 3,600 lbs.of toluene. The mixer is run for twelve hours and a clear cementresults. The temperature of this cement is raised to 160 F. and thecement is then mixed with 2,800 lbs. of water also heated to 160 F. andcontaining 48 lbs. of the sodium salt of nonylphenylether ofpolyoxyethylenesulfate containing about 4 ethylene oxide units.

The coarse emulsion at 160 F. obtained in the sigma blade mixer is thenpassed once through a homogenizing circuit comprising in series the twoforms of disperser 112 and 112A described above in connection with FIG.2, each operated at 5,200 rpm with the aid of a 15 horsepower motor. Theresulting fine cementin-water emulsion is then delivered to a heatexchanger 113A and therein cooled to 135 F. and then delivered once at apump pressure of 4,000 p.s.i. developed by plunger pump 113D driven byhorsepower motor M through the constriction of a resiliently restrictedorifice type industrial homogenizer (model K24-3BS manufactered byManton-Gaulin Manufacturing Company, Inc.), from which the resultingaqueous emulsion of solvent/polymer solution is delivered to storage 113after cooling to about F. in heat exchanger 113F.

The fine cement-in-water emulsion is then injected as illustrated at114E in FIG. 4, with a stream of steam 114C expanded down to asub-atmospheric pressure measured as a vacuum in the range of 8 to 10inches of mercury depending on the rate of feeding of the steam at 114C,the emulsion at 114E and additional steam introduced downstream of 114E,which in total were fed in the proportion of about three pounds of steamper four pounds of the toluene content of the cement, about one third ofthis steam being supplied at 114C and the remainder being supplied inabout equal parts at 114F and 1 MG spaced one foot and two feetdownstream from 114E, respectively. The output of the unit 114 afteraugmenting of the flow and solvent stripping at 114G is passed through apressure gradient controlling means l14I-I which may be in the form of apipe constriction, a valve, or an extended length of conduit, and thenceto the segregator means (15, FIG. 1, 1 15 or 215, FIG. 3). Thesegregator 215 may be a corregated plate type heat exchanger asillustrated in the aforesaid copending application, no heat beingsupplied to the intervening spaces between the pairs of plates, but inaccordance with the present improvement the segregator employed in thisexample is one in which the gas and liquid latex phases are bothsubjected to centrifugal force to effect the segregation or coalescenceof the latex phase droplets, e.g. a centrifugal pump 115, wherein thetwo phases are subjected to a pressure drop because the outlet of thepump is connected to the vacuum separator 216 at the same time thatcentrifugal accelleration is being imparted to throw the latex parti'cles together to form larger droplets. The pressure drop in the pump1115 is l 15 by the means 114A and a similar pressure gradientcontrolling means 115A, The gaseous and liquid droplet phases which havebeen passed i arough the segregator 115 are delivered-to a separator 15connector through a condenser system to a source of vacuum of between'26and 29 inches of mercury. The flow rates of the steam and of the aqueousemulsion of solvent/polymer solution are adjusted to attain as large athroughput as possible without detrimental foaming producing carryoverfrom the separator, and the continuous vapor phase free of any foam ispassed to the condensing equipment, where the water in excess of thequantity azeotroped with the solvent is condensed in a first stage, theremaining azeotrope being condensed in a second stage and separatinginto solvent and water layers immediately on condensing. The solvent issubstantially all accounted for in the gaseous phase; the separatedlatex from this initial stripping operation containing about 18 percentsolids, dry basis, and is useful as a dilute adhesive composition.

EXAMPLE 2 Modification of the Stripped Residual Solvent Containing LatexTo one-fourth of the stripped latex from Example 1, is added 2.0 lbs. ofmonosodium phosphate which reduces the pH to 5.5 and this acidic latexis fed at 3,000 p.s.i. to the orifice homogenizer 326 and thereafter fedto the concentrating circuit 1220-1216 whereby the latex solids areraised to 65 percent.

EXAMPLE 3 Polar Modification of the Stripped, Residual SolventContaining Latex I To one-fourth of the latex from Example 1, is added20 lbs. of octylacrylate and 2.0 lbs. of cumene hydroperoxide, and 1.0lb. of tetraethylenepentamine. After passing through the homogenizer 326at room temperature the latex is subjected to polymerization by heatingto 120 F. for 6 hours, and is then concentrated to a solids content of62 percent in concentrating circuits 1216, 1220.

EXAMPLE 4 Polar Modification of the Stripped and Concentrated Latex withthe Aid of a High Pressure Homogenizer One-fourth of the latex fromExample 1 is concentrated to 62 percent solids by concentrating unit1220 and 1216 with recycle.

To the concentrated latex is added 16 lbs. of dodecylacrylate, 4 lbs.ethyleneglycoldimethacrylate ester, 2 lbs. cumene hydroperoxide, and 1lb. of tetraethylenepentamine, the cross-linking agent, monomers, andcatalyst are obtained from recievers 1224a, 1224c and 1224b and thecombination is mixed in the mixer 1224 and pumped at 4,000 p.s.i.through homogenizer 1226 then heated to polymerize the monomer materialat 1225 then cooled with the aid of the heat exchanger 1232 and is sentto storage 1233.

EXAMPLE 5 Preparation of Polyisoprene Latex Polyisoprene rubber GoodyearTire and Rubber Companys Natsyn type 200E is mixed in the laboratoryBanbury for 4 /2 minutes and dumped at a temperature of 360 F.

To a sigma bladed mixer is added 430 lbs. of the Banbury treatedpolyisoprene prepared similar to heretofor, 3,470 lbs. of toluene and 26lbs. of oleic acid and on mixing overnight a smooth cement results.

An aqueous alkaline solution is prepared by dissolving in 2,270 lbs. ofwater, 17 lbs. of oleic acid and 6.6 lbs. of potassium hydroxide. The3,920 lbs. of polyisoprene cement containing 6 percent by weight oleicacid based on the rubber is mixed with the 2,290 lbs.

of alkaline soap solution. With very little agitation the mix becomes afluid coarse emulsion.

The coarse emulsion is placed in a stainless steel tank with a bottomopening connected to a homogenizing apparatus 112 which is provided witha recycle line to said tank. The rough emulsion is pumped through thehomogenizing apparatus 112 for a period of 1 hour and 30 minutes and thetemperature rises from 30 C. to 65microscopic observation of theresulting emulsion shows it to be of precursor latex particle size. Thelatex is then cooled and fed into a resiliently restricted orifice typehomogenizer (l13D-1 13E) at 5,000 p.s.i. and at a temperature of 40 C,and is stored (as at 113). At 40 C said latex is steam stripped in theapparatus 114-1146 and thereafter segregated and collected (as at 216).To assure stability of the latex temperature are held at 6070 C duringthe stripping operation. The polyisoprene latex obtained from thestripping operation has about 20 percent solids and contains residualsolvent.

EXAMPLE 6 Modification of Residual-Solvent Containing Polyisoprene LatexOne-fourth of the latex prepared by Example 5 is concentrated to solidsin the range of 40 percent and designated 6-A. Another fourth is passedthrough the Gaulin homogenizers at a pressure of 6,000 p.s.i. at 40 C.and this latex concentrated to a somewhat higher level of solids contentand was designated 6-B.

EXAMPLE 7 Preparation of Polyisoprene Latex with Increased MolecularWeight To latex designated 6B from Example 6 is added 3 lbs. ofdicumylperoxide from 1223a and the mixture pumped at 4,000 p.s.i.through the homogenizer 1226 and then through the heater 1225 and thencooled in heat exchanger 1232 and sent to storage 1233.

EXAMPLE 8 By repeating Example 5, in the same equipment as employed inFIG. 3, but with a segregator such as the segretator 215 substituted forthe segregator 115 of FIG. 3, similar results and economies areobtainable;

EXAMPLE 9 By repeating Example 5 in the same manner and in the sameequipment except that when the raw emulsion steam aerosol is formed allof the steam is admitted at 1 14C.

EXAMPLE 10 Preparation of Ethylene-Propylene Rubber Latex To a sigmablade mixer is added 500 pounds of ethylene-propylene rubber (Enjay EPRrubber)* and 404 pounds of toluene, and after mixing 12 hours a clearrubber cement is obtained. A coarse emulsion is made by combining 4,540pounds of this cement with an aqueous solution comprising 2,260 lbs. ofwater and 8.4 lbs. of 36 percent hydrochloric acid and 50 lbs. of 50percent active quaternary ammonium compound sold under the trade nameRedicote E-l1 and consisting principally of the compound having thefollowing formula:

1. AN IMPROVEMENT IN A PROCESS FOR PRODUCING LATEX, THE PROCESS IMPROVEDBEING OF THE TYPE IN WHICH AN AQUEOUS EMULSION OF POLYMER/SOLVENTSOLUTION WHICH HAS BEEN PREPARED WITH THE AID OF AN EMULSIFYING AGENTAND HAS AS ITS DISCONTINUOUS PHASE DROPLETS OF SUCH SOLUTION OFPRECURSOR LATEX PARTICLE SIZE THE POLYMER OF SUCH SOLUTION BEINGESSENTIALLY ORGANIC SOLVENT SOLUBLE OR DISPERSIBLE AND ESSENTIALLY WATERINSOLUBLE, AND THE SOLVENT OF SUCH SOLUTION BEING A ORGANIC SOLVENT FORTHE POLYMER, IS CONVERTED FROM AN EMULSION TO A FLOW OF AEROSOL OFLATEX, OF THE POLYMER IN AN AQUEOUS/SOLVENT VAPOR PHASE, AND IN WHICHTHE AEROSOL DROPLETS OF LETEX ARE THEN COALESCED INTO LARGER DROPLETS INTHE FLOW TO FACILITATE SEPARATION OF THE LATEX FROM THE GASEOUS PHASE INA SEPARATING ZONE MAINTAINED AT A REDUCED PRESSURE WHICH CAUSES MOVEMENTOF THE FLOW THERETO, AND SAID IMPROVEMENT CONSISTING ESSENTIALLY INSUBJECTING THE AEROSOL, ON ITS WAY TO THE REDUCED PRESSURE ZONE, TO THEACTION OF CENTRIFUGAL FORCE SUFFICIENT FOR EFFECTING SUCH SEGRGATION ORCOALESCENCE OF THE NON-GASEOUS PHASE.
 2. The process according to claim1, wherein the said polymer is a polymer of ethylenically unsaturatedmonomer material containing from 2 to 20 carbon atoms.